IMAGE: Prapiroon's winds had dropped to less than 35 knots (~40 mph) when the TRMM data were collected on Oct. 18. Despite the drop in wind speed, some powerful thunderstorms around...
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Credit: SSAI/NASA, Hal Pierce

Heavy rainfall returned to Typhoon Prapiroon for a brief time on Oct. 18 when NASA's TRMM satellite passed overhead. Prapiroon is battling strong wind shear and is expected to transition into an extra-tropical storm in the next day.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite captured rainfall data on Prapiroon twice on Oct. 18 when it passed overhead. The first orbit was at 0845UTC and the second at 1019 UTC. TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data show that rain associated with Prapiroon was falling at a rate of over 75mm/hour (~3 inches) in a feeder band northwest of the center of circulation.

Some of the rainfall occurring over Japan on Oct. 18 was being caused by a frontal system that was interacting with tropical Storm Prapiroon.

At NASA's Goddard Space Flight Center in Greenbelt, Md., Hal Pierce of the TRMM team created a 3-D image of the storm using TRMM PR data received with the 1019 UTC (6:19 a.m. EDT) orbit. Prapiroon was once a powerful typhoon with winds of 100 knots (~115 mph). Prapiroon's winds had dropped to less than 35 knots (~40 mph/65 kph) when the TRMM data were collected. Despite the drop in wind speed, some powerful thunderstorms around Prapiroon's center were still reaching heights above 12 kilometers (~7.6 miles).

Just five hours after the second TRMM satellite overpass, the Joint Typhoon Warning Center noted that "animated infrared satellite imagery showed deep central convection has unraveled and sheared north of the low level circulation center."

Prapiroon is undergoing transitioning while battling strong wind shear and is expected to become extra-tropical by Oct. 19.

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